Tuesday, November 19, 2013

A few words today about SYNAPTID sea cucumbers! (i.e, Family Synaptidae). These are a family of unusual sea cucumbers which are observed in shallow/SCUBA depth waters in the tropics! There are over 120 species of synaptids which occur primarily in the Indo-Pacific.

Synaptid sea cucumbers move pretty actively via peristalsis (i.e., body pulsates in a manner similar to that of worms. They seem to have lost any external manifestations of tube feet..

Image by Jay Dryden

Synaptids have a well-developed array of feather-like feeding tentacles they use to move organic food into their mouths. Here's a video that shows one alive and kicking!

As the video shows, synaptids move along the bottom in a snake-like-fashion using their tentacles to move food into their mouth as they move as this species (Synapta maculata) from Lembeh Strait in Indonesia is doing..

Image by Bernard DuPont

This shows how long these get.. Some reach 6 FEET long...

Image by shamsulazar

Some are decoratively patterned!

Image by ania115

But while some species are huge and massive, others are tiny and form HUGE aggregations...

In Synaptula spp., you'll often see hundreds of them on a single sponge! What I like to think of as a veritable city of sea cucumbers!

See all those wormy white things on the sponge? THOSE ARE SEA CUCUMBERS! (the genus Synaptula sp.).

image by Enice Khoo (mermate)

Another dense sponge colony overrun by Synaptula!

image by Bernard DuPont

Here's a less populous one..

image by Tom Puchner

More!

image by Alfonsator

some of them crawl around on purple sponges!

Image by Wild Singapore

image by Wild Singapore

This is not the same sponge colony but a close up of a different one.. it gives you an idea of what's they look like (close up).

image by Rob Jeff

But what are they doing? Presumably this posture of them reaching upright into the water is feeding,i.e., taking advantage of the water currents. Sea cucumbers living on a sponge is actually a pretty convenient place to live.. as sponge filter water, they likely accumulate all sorts of potential food particles that Synaptula can take advantage of...

Amazingly, this is only the TIP of the iceberg where these animals are concerned..but that will have to wait for a future post!

Tuesday, November 12, 2013

What are Brachiopods?
Brachiopods are actually a PHYLUM of animals. That's right a whole GROUP of animals that most folks have probably never heard of!

image by Herman Giethoom

Brachiopods are a very old, old group of invertebrates with a relatively rich fossil record. They have two shells (and are superficially similar to bivalves, e.g; clams and mussels) but are better known in several other ways...

Brachiopods are one of the few groups of marine animals which live ONLY in the Ocean! (Echinoderms being one of the others...)

Some places you learn about some new mammal, but HERE at the Echinoblog? you learn about a whole PHYLUM of animals in five easy steps!

1. What does the name mean? Brachiopoda, when you break it down: "brachio"= arm and "poda"= foot. Wha? The Arm foot?

The name refers to a structure known as the pedicle. That's the purple stalk bit that is anchoring the animal down to the substrate. This is how the pedicle looks
in the group informally known as the "articulate" brachiopods. Arm refers to the muscular arm-like aspect and "foot" to its use (or disuse) in attatching to the bottoms.

The pedicle manifests in two different ways relative to which of the two major groups of brachiopods you are looking at!

One group has been referred to as the "Articulate" brachiopods. And yes; they are very well spoken thank you. ha ha.you have now caught up with the jokes:

Yes. I know the symmetry seems strange and can be oddly difficult to "get" the first time around. Here are some brachiopods...

image by mpjones_007

Image by Alexander Semenov

and here's some clam for comparison (positioned for convenience!)

Image by Royston Vasey

3. What/How do they eat?
Brachiopods have a feathery feeding structure called a lophophore! Brachiopods are basicaly suspension feeders. Water flows in and over the lophophore and tiny finger-like bits called cilia pick the food up!

Here's some reality from the very talented Arthur Anker showing the lophophore with the animal's valves open!

And here is the diagrammatic approach that gives you a general idea of what you're looking at.... The animal below has been turned upside down to show parallel orientation with the pic above...

4. In the Paleozoic (roughly 250-500 million years ago), brachiopods were once THE happening invertebrate!

image by David Cartier

Earliest known fossils date back to the Cambrian (600 million years ago-but probably more), but the time of the brachiopod was in the Paleozoic! (bear in mind how vast a time period 250 million years is.. that's MUCH older than humanity..). They dominated in diversity and abundance. This was their "time"... Sadly, most brachiopods underwent a huge extinction at the end of the Paleozoic...

According to the World Brachiopod Database only about 385 species occur today from the ~30,000 described (mostly fossil) ones!!

Many of these species live in out of the way and isolated places...

Here is a gorgeous pic of Coptothyris adamsia from the Sea of Japan

Image by Alexander Semenov

Here is Laqueus californica from Monterey Bay in some pretty amazingly high densities...

and more from Alexander Semenov: Hemithyris psittacea (Rhynchonella psittacea)

5. Geology! Fossil Brachiopod Shells are sometimes replaced by Pyrite! (aka Fool's Gold)
In the fossil record, the "shells" (called valves) of brachiopods sometimes undergo a process in which they are replaced with pyrite aka fool's gold!

This makes them golden and sparkly!

Image by jsj1771

Image by E. Sese

Image by JS1771

5a! More Geology Fun! Brachiopod valves are often found in cross sections of rock!
Geologists know the value of a good cross section! Brachiopods are VERY abundant in Paleozoic rock. And if you cut through the shells of one you get some pretty distinctive impressions in the rock..

Image by Maitri

Sometimes there are minerals such as agate!

Image by Captain Tenneal

Brachiopod shells can be pretty dense and sometimes you see a lot of them! Sometimes you see some neat rare stuff.. like this soft-part preservation of a lophophore!

About Me

I pursue starfish related adventure around the world with a critical eye and an appreciation for weirdness.
Support has been courtesy of the National Science Foundation but the views and opinions presented herein are mine and do not reflect the opinions of them or any affiliated institutions.
Need to hire an invertebrate zoologist/marine biologist? Please contact me!